Effect of cooking conditions on cholesterol oxidation and astaxanthin in dried salted shrimp

Abstract

Dried salted shrimp is a product made from raw shrimps, which are usually cooked and dried under direct sunlight. Brine cooking is an important step during the production of dried salted shrimp as it promotes changes that affect the product's end quality. The aim of this study was to evaluate the effect of brine concentration and boiling time on cholesterol oxidation products (COPs) formation and the concomitant changes in astaxanthin content and fatty acid profile in shrimp during cooking, sun drying, and storage. Boiling conditions did not affect COPs formation in shrimp after cooking. However, increased brine concentration and boiling time promoted high astaxanthin retention in cooked shrimp. During the first 24 h of sun drying, COPs formation in dried salted shrimp was influenced by the interaction between brine concentration and boiling time; in fact, the lowest COPs levels were observed in samples boiled at low brine concentration and short cooking times, as well as those boiled in brine with high salt concentration and long cooking times. Most astaxanthin (ca. 78%) present in cooked shrimp was degraded during solar drying. During storage, PUFA decreased, and a concomitant astaxanthin degradation and COPs formation in dried salted shrimp were observed. Neither boiling time nor storage at dark of dried salted shrimp prevented these changes.Practical applications: The content of oxysterols in cooked dried shrimps can be minimized by optimizing the processing conditions to minimize the oxidation. This is useful for processors and consumers to reduce the intake of these toxic forms of cholesterol.

Improvement of Pacific White Shrimp (Litopenaeus vannamei) Drying Characteristics and Quality Attributes by a Combination of Salting Pretreatment and Microwave

“…This may be due to the changes in structural conformations induced by salinization and the protein lost its binding affinity to small molecules including astaxanthin, thus increasing the content of free astaxanthin. However, at the same time, astaxanthin oxidized by thermal oxidation [ 44 ] and higher salt concentrations led to an increased degree of protein denaturation, and when the part of the protein bound to astaxanthin completely denatured, the degradation rate of astaxanthin would be greater than the formation rate, resulting in a decrease in the astaxanthin content at high salt concentrations (≥6%). This phenomenon can also be confirmed by the changes in protein secondary structure in Figure 5 , where the degree of protein denaturation increased when the salt concentration increased from 4% to 8%.…”

Cholesterol and stigmasterol within a sunflower oil matrix: Thermal degradation and oxysterols formation

“…Although this is not an unusual distribution [14,32], 7-keto derivatives are more frequently found as the major ones, mainly in advanced stages of oxidation. This point was also critical for epoxydes behavior, which started to decrease afterwards, with betaisomers being formed in higher amounts than alpha ones, as the steric hindrance of hydroxyl group in position 3 determines [33].…”

“…Among these influencing factors, processing, cooking and storage conditions clearly affect the oxysterols formation [12][13][14].…”

Astaxanthin for the Food Industry

“…This fact is very important during the production of smoked salmonoids and dried salted shrimp. Studies showed that the astaxanthin content in cooked shrimp decreased by 78% after four days of direct sun drying due to photodegradation [ 46 ]. The content of this pigment was much lower than the content obtained in a jet-spouted bed-drier at 80, 100 and 120 °C [ 47 ].…”